This invention relates generally to scanners. More particularly, this invention relates to scanners that may be used to read hidden indicia, machine-readable codes and other types of markings that have varying emissivity values.
Various marking techniques have been used for identification and authentication purposes. For example, machine-readable codes (e.g., bar codes, 2D matrices, etc.) and other types of indicia have been used to attach important information to documents and other types of products such as pharmaceuticals, clothing, and retail accessories. Such machine-readable codes traditionally include information of the origin, manufacturer, history, ownership, and/or other features or details of the product to which the code is attached. Many goods to be distributed, such as pharmaceutical products, postage labels, packages, etc., often use bar-codes to provide manufacturing, shipping, packaging, and other product information. Alternately, retail product labeling traditionally utilizes machine-readable codes to provide pricing information for particular products.
As the need for protection against counterfeiting has increased, the use of various types of “invisible” marking techniques have become more prevalent. Ultraviolet (UV) and infrared (IR) scanning and imaging systems, for example, are now widely used to detect non-visible information. Such systems traditionally rely on reflected light to detect special inks with particular properties related to a particular wavelength of light. One benefit of using these systems is that the special inks may not be visible when illuminated with light from the visible spectrum (i.e., about 400-700 nm). In this manner, an individual is unable to tell whether the product contains “invisible” markings with the naked eye. These special inks, however, are traditionally visible when illuminated with light in the UV spectrum and/or IR spectrum, respectively.
Magnetic materials have also been utilized as part of machine-readable codes. Such magnetic indicia are detected by immersing the magnetic indicia into an electromagnetic field.
Despite the early success of the above-described types of detection systems, these systems have become vulnerable to alternate forms of detection. For example, hidden indicia using special inks can be detected or even made visible through the interaction of the ink with radiation. It is therefore desirable to provide improved machine-readable codes or indicia that is protected from alternate forms of detection.
Furthermore, many traditional types of indicia and detection systems have proven to be susceptible not only to detection, but also to copying. For example, traditional bar codes that may be found on food products, driver's licenses, or retail accessories may be copied with a Xerox machine. The information stored in the original bar code may then be extracted from the Xerox generated bar code with very little (if any) extra effort. Moreover, the information stored in the Xerox generated bar code may be extracted using the same detection device necessary to extract the information stored in the original bar code.
Invisible and hidden indicia may also be copied with, for example, conventional office supplies (such as highlighters and UV light bulbs). The use of traditional types of hidden indicia may be copied so easily that amusement parks, for example, do not rely on hidden indicia alone. When stamping patrons' hands for readmission, many amusement parks use invisible ink that may be detected by UV light. In addition many amusement parks change the shape of the stamp on a daily basis (as a security measure) because the ink is so easily obtained and reproduced.
Generally, many detection systems that detect and/or read bar-codes or other types of markings may detect markings that are visible or become visible when presented with a source of energy (e.g., barcodes on boxes). These markings are read by reflection or absorption of an impinging radiation source. The required source of radiation generally has to correspond to the light reflection or absorption properties of the markings. As such, these systems cannot detect markings, which contain information that is not encoded by means other than light reflection. Nor may these systems detect markings that do not become visible even when presented with radiation. It therefore is desirable to have systems and methods that may detect invisible indicia and decipher potential codes without using reflected energy.